Removal during NodeList iteration breaks loop

[nielsdos]

Description

The following code:

<?php

$doc = new DOMDocument();
$doc->preserveWhiteSpace = false;
$doc->loadXML(
    <<<EOXML
    <x>
        <item1 />
        <item2 />
        <item3 />
        <item4 />
        <item5 />
    </x>
EOXML
);

foreach ($doc->documentElement->childNodes as $i => $node) {
    echo $node->localName . PHP_EOL;
    if ($i === 2) {
        $node->remove();
    }
}

https://3v4l.org/TJLvF

Resulted in this output:

item1
item2
item3

But I expected this output instead:

item1
item2
item3
item5

Source: nielsdos#93 (comment)
Credits to @veewee. Similar issue exists for attributes.

PHP Version

Since always

Operating System

No response

[damianwadley]

This behavior is correct: childNodes is a "live" NodeList, and changing the children is reflected immediately in the list. Which also means the current i now points to what would have been the next child, thus when the loop advances it skips an item.

Javascript implements it that way. Does PHP really want to be different about it?
https://jsfiddle.net/54hoLzqv/
(keep in mind that it's the console output which shows items 1,2,3, while the document had 3 removed and so ends up with items 1,2,4)

Same for attributes, which is also a live NodeList.

Obligatory "this behavior has existed for a really long time so is there a good enough reason to change it now?"

[nielsdos]

The example is badly chosen, I've corrected the example. Then you can see that the iteration stops despite the list being needing to be live.

Obligatory "this behavior has existed for a really long time so is there a good enough reason to change it now?"

Obligatory "we kind of worked around that issue": https://wiki.php.net/rfc/opt_in_dom_spec_compliance